The setting up of the "prophetic model" was the work of generations who had not known the prophetic times. They searched this "model" with a single criterion: the Sunnah of the Prophet. The Sunnah included various elements about the Prophet’s deeds (gestures, attitudes, words, silences, etc.), consigned by his companions and compiled in corpora of narrative and normative texts. The first attempts of codification were dated from the early 8th century. A broad selection made in the 9th century was at the origin of the major compilations. The most famous ones are the Sahīh ("the Authentic") by al-Bukhārī (died in 870) and by Muslim (died in 875). The Prophet’s words, collected and sorted out by traditionalists according to their reliability, were designated under the generic term hadīth [see Islam module I page 4].
Sunnism was often presented as some orthodoxy, although this term of Christian origin did not seem appropriate for a tradition devoid of church authorities and of a single doctrine. However it owed its development to the influential body of Muslim scholars, the 'ulamā’. These legal theologians justified their legal, ideological or religious positions by basing them on the Sunnah.
The development of Sunnism in the 10th century - as the expression of the community consensus - happened among particularly violent theological objections. These new religious "discords" divided the Muslim community because of their impact on political life. Against the "extremisms" - Shiism and "innovations" like the rationalist Mu'tazilite doctrine -, the "People of the Community and of the Tradition" resisted by building up a prophetic tradition based on the hadīth, meant to be both the only way and the Islamic norm because of its exemplarity versus Shiism. In Shiism, the Imām was the only one to reveal the hidden meaning of the Holy Word. Purified from destructive "innovations", the Sunni “doctrine” was supposed to be a return to the "right balance". The Sunni tradition developed in the late second century and the early third century of Hegira with major works: theological treatises, legal treatises, Quranic exegeses, compilations of prophetic traditions, and compilations by Companions.
The struggles against "innovations" influenced legal schools and theological doctrines, for example the Mu'tazilite doctrine. This law school, highly influential in Iraq from the 8th century to the 10th century, claimed that the Quran was created to disseminate God's message as a speech transmitted through human words, to be understandable by a society in a given time.
Faced with “subversive” doctrines, the Ash'arite current of thought played a key role in the development of the Sunnah, now considered the most influential school of thought in the Muslim world. This doctrine was named after Ash'arī, a theologian living in the city of Basra in the 10th century. Trained by a Mu'tazili scholar, al-Ash'arī became his master’s adversary and refuted the theses of the Mu'tazila by using rational arguments. His doctrine – that was then developed by his followers - became a "middle way" between the strict literalism used to interpret the Quran and the rationalist study. According to al-Ash'arī, the Revelation prevailed over reason, but reason was useful to refute the "errors" of all the "enemies" of Islam. These “enemies” were internal “enemies” like Mu'tazilites and Shiites, but also Jews, Christians and Manichaeans. Al-Ash’arī defended in particular the idea of an uncreated and unchanging Quran, the Word of God, and the idea of predetermination. He also deepened the knowledge on the founding Sunni dogmas about Resurrection, Heaven and Hell.
In the 10th century, the ‘Abbāsid Empire was threatened by the emergence of rival Arab caliphates. In the following centuries, the power fell into the hands of Berber, Turkish and Kurdish dynasties, shaking the model of the Rightly Guided Caliphate. The question of governance was debated by theologians, jurists and philosophers. What legitimacy did the new sultanates hold? What should be the qualities of a sovereign? Should they rebel against despots? The Mu'tazila based the legitimacy of the community leader on his personal merits. Ash’arite theologians justified the allegiance to the Sultans – chosen by “consultation” or not - in the name of the community interest. The guide of the community needed to be Muslim, to be "just" and to enforce Islamic Law.
Supporters of the Sunnah – who also supported the gathering of believers - acquired a dominant position in the second half of the 10th century and the 11th century. They received support from the political power in their fight against the extremist Shiite “deviations”. Three names were often cited as the "founders" of the “middle way”: al-Shāfi'ī (767-820), also named nāsir as-sunna (who gave the victory to the Sunnah), al-Ash'arī and al-Ghazālī. Sunnism was taught in the new madrasas founded by the Seljuk Turks and the Berber dynasties in the Muslim West (Maghreb and Andalusia). In the 11th century, in order to "restore" Sunnism and counter the most extreme Shiism, Nizām al-Mulk, vizier of the Seljuk Sultan, founded state schools of religious sciences to spread the Ash’arite doctrine and also founded a law school for al-Shāfi'ī.
Ash'arism supported the legitimacy of the tribe of Quraysh - the tribe of the first successors of the Prophet. The first four caliphs, the "Rightly Guided" (632-661), were legitimized by consultation and by the choice of an assembly (shūra). Sunnism sacralized these outstanding caliphs, who were related to the Prophet by blood or by marriage alliances. Obedience was due to the sovereigns, who enforced the Law of Islam (Sharī'a) interpreted by case law specialists according to given rules. Major Sunni treatises defended the legitimacy of the Caliphate institution since the Rightly Guided, by adapting it to their times, for example Al-Māwardī (11th century) under the 'Abbasids and Ibn Taymiyya (13th century) at the time of the Mamluk sultans of Egypt and Syria.
Sunnism has often been reduced to the "Profession of Faith" and to the five obligatory duties known as "Pillars of Islam", a term taken from one famous hadīth. But Sunnism should not only be defined by the adoption of these principles and the adoption of theological ideas. Supporters of the Sunnah also adopted legal discourse, practice of law and a doctrine. The legal systems - known under the names of schools - were built up alongside heated debates from the 9th century to the 12th century. These legal systems were then “individualized” from the second century of the Hegira.